Temperature derivative based launch method for fire suppression systems

ABSTRACT

A fire suppression system is provided including at least one spray head. A drive source is coupled to the at least one spray head by a supply line that delivers an extinguishing medium thereto. A control valve is connected to the supply line between the drive source and the at least one spray head. The system includes at least one temperature indicator for measuring a surrounding temperature. A control unit is operably coupled to the drive source, the control valve, and the at least one temperature indicator. The control unit monitors a rate at which the temperature measured by the at least one temperature indicator changes to determine a location of a fire.

BACKGROUND OF THE INVENTION

The invention relates generally to fire suppression systems and, moreparticularly, to the detection of the location of a fire by a firesuppression system.

Conventional fire suppression systems typically include sprinklers ornozzles positioned strategically within an area where fire protection isdesired, such as inside a building. The sprinklers remain inactive mostof the time. In some fire suppression systems, such as dry pipe systems,methods of detecting a fire may be based on the air flow or rate ofchange in pressure in the system. In other systems, a fire may bedetected using flame or smoke detection, or alternatively, thesprinklers may detect a fire and activate as a direct result of theheat.

Fire suppression systems that activate in response to air flow are quickto activate, however, these systems are unreliable and frequentlygenerate false alarms. Fire suppression systems responsive to the rateof change of a pressure within the system are quick to activate, buthave problems with measurement reliability due to the high pressure inthe system. Conventional fire suppression systems fail to quickly andaccurately detect the location of a fire. As a result, systems areover-designed to combat larger fires to compensate for the slowness andinaccuracy of the system. Such over-designing adds significant cost tothe system because additional components and more costly components,such as larger diameter pipe for example, are included in the system.

BRIEF DESCRIPTION OF THE INVENTION

According to one embodiment of the invention, a fire suppression systemis provided including at least one spray head. A drive source is coupledto the at least one spray head by a supply line that delivers anextinguishing medium thereto. A control valve is connected to the supplyline between the drive source and the at least one spray head. Thesystem includes at least one temperature indicator for measuring asurrounding temperature. A control unit is operably coupled to the drivesource, the control valve, and the at least one temperature indicator.The control unit monitors a rate at which the temperature measured bythe at least one temperature indicator changes to determine a locationof a fire.

According to another embodiment of the invention, a method of detectingand determining a location of a fire with a fire suppression systemhaving a plurality of temperature indicators positioned adjacent aplurality of spray heads is provided including measuring a surroundingtemperature at each of the plurality of temperature indicators. A changein temperature over time is calculated for each of the plurality oftemperature indicators. The temperature indicators having a change intemperature over time greater than a predetermined threshold areidentified.

According to another embodiment of the invention, a method of activatinga fire suppression system having a plurality of temperature indicatorspositioned adjacent a plurality of spray heads and a plurality of firesensors coupled to the system is provided including detecting a presenceof a fire. A drive source and the plurality of temperature indicatorsare activated. The surrounding temperature at each of the plurality oftemperature indicators is measured. A change in temperature over time iscalculated for each of the plurality of temperature indicators. Thetemperature indicators having a change in temperature over time greaterthan a predetermined threshold are identified. The fire suppressionsystem is activated once temperature indicators having a change intemperature greater than a predetermined threshold are identified.

These and other advantages and features will become more apparent fromthe following description taken in conjunction with the drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

The subject matter, which is regarded as the invention, is particularlypointed out and distinctly claimed in the claims at the conclusion ofthe specification. The foregoing and other features, and advantages ofthe invention are apparent from the following detailed description takenin conjunction with the accompanying drawings in which:

FIG. 1 is a schematic diagram of a fire suppression system according toan embodiment of the invention; and

FIG. 2 is a schematic diagram of another fire suppression systemaccording to an embodiment of the invention.

DETAILED DESCRIPTION OF THE INVENTION

Referring now to FIG. 1, an exemplary fire suppression system 10including a drive source 20 and a plurality of spray heads 40 isillustrated. In one embodiment, the spray heads 40 include nozzles withsmall openings arranged to spray an aqueous liquid mist. The spray heads40 of the fire suppression system 10 may be positioned in the samegeneral area of a building as the drive source 20, or alternatively, maybe separated from the drive source 20 by a bather, such as a wall forexample. A supply line 15 extends from the drive source 20 to theplurality of spray heads 40 to supply an extinguishing medium thereto.In one embodiment, the extinguishing medium used in the system 10 iswater. The drive source 20 may include a pump and a motor for operatingthe pump and is connected to an extinguishing medium source 25, such asa pipeline network or a tank. A control unit 50 is operably coupled tothe drive source 20 to activate the drive source 20 when a fire has beendetected.

The supply line 15, including branch supply lines 15 a and 15 b leadingto the spray heads 40, may be filled with a gas, for example anincombustible gas such as nitrogen or air. The gas prevents the supplyline 15 and the branch supply lines 15 a, 15 b from freezing. Instead offilling the entire supply line 15 including the branch supply lines 15 aand 15 b with gas, it is possible to fill only the portion of the supplyline 15 closest to the spray heads 40. In such instances, the end of thesupply line 15 adjacent the drive source 20 includes a liquid. Theportion of the supply line 15 that includes a gas is separated from theportion of the supply line 15 having a liquid by a control valve 17 toprevent mixing of the gas and the liquid. The control valve 17 may be asolenoid control valve, a pilot valve, or any other type of valve havinga control mechanism for opening the valve. The control valve 17 may belocated at any position along supply line 15 between the drive source 20and the spray heads 40. The control valve 17 is operably coupled to thecontrol unit 50, such that when the drive source 20 is active, thecontrol unit 50 opens the control valve 17 to allow extinguishing mediumto flow to the spray heads 40.

As illustrated, the system 10 may include a gas compressor 30 connectedto the supply line 15 by an output pipe 37. The gas compressor 30 isused to initially fill the supply line 15 and to refill the supply lineto a desired pressure when necessary. The gas compressor 30 is also usedto maintain a standby pressure in the supply line 15 when the drivesource 20 is inoperative. If the standby pressure decreases with time toa level below a predetermined threshold, such as due to leaks in thesystem 10 for example, the gas compressor 30 increases the pressure byrefilling the supply line 15. The fire suppression system 10 may alsoinclude one or more fire sensors 45, located in the vicinity of thespray heads 40 to detect a fire condition. Exemplary fire sensors 45include smoke detectors, temperature sensors, infrared or other lightdetectors which are used to sense a fire condition and generate anelectrical signal indicative thereof. Such signals are transmitted tothe control unit 50 to activate the fire suppression system 10. Theabove described fire suppression system 10 is exemplary and other firesuppression systems are within the scope of this invention.

The fire suppression system 10 may also include one or more temperatureindicators. Exemplary temperature indicators 60 include thermocouplesand other temperature sensors. In dry pipe fire suppression systems, thetemperature indicators 60 may be disposed within a portion of the supplyline 15 between the control valve 17 and the spray heads 40. In oneembodiment, the temperature indicators 60 are positioned in the branchsupply lines 15 a, 15 b adjacent each of the spray heads 40. In anotherembodiment, illustrated in FIG. 2, the one or more temperatureindicators 60 may be used to measure the ambient temperature adjacentthe exterior of the spray heads 40. Each temperature indicator 60 may belocated in the vicinity of a spray head 40 outside of the supply line 15or alternately, may be mounted to a portion of each spray head 40. Inembodiments where the temperature indicators 60 are located external tothe supply line 15, the fire suppression system 10 may be either a drypipe or a wet pipe system.

The temperature indicators 60 may continuously measure, or alternately,may sample at intervals the surrounding temperature. The temperaturesmeasured by each of the temperature indicators 60 are communicated tothe control unit 50, where they are monitored over time to determine therate of change of the temperature at each device 60. In embodimentswhere the temperature indicators 60 are located in the supply line 15, arate of temperature change greater than a predetermined thresholdindicates that an adjacent spray head is open. Thus, the temperatureindicator 60 measuring the fastest change in temperature over timeidentifies which spray heads 40 in the system are open, and thereforethe general location of a fire. In embodiments where the temperatureindicators 60 are attached to or adjacent the exterior of the sprayheads 40, a temperature indicator 60 having a rate of change greaterthan a predetermined threshold indicates the presence of a fire nearthat temperature indicator 60.

In embodiments where the temperature indicators 60 are disposed withinthe supply line 15, the rate of temperature change measured at eachdevice 60 may also be used to detect and identify the location of a gasleak. In addition, the fire suppression system 10 can easily identifyand generate an alarm to indicate that a temperature indicator 60 hasmalfunctioned. If the control unit 50 does not receive a signal from atemperature indicator 60 but does receive signals from the surroundingtemperature indicators 60, the system 10 can determine that thetemperature indicator 60 not providing a signal to the control unit 50has failed.

When the fire suppression system 10 is in a “detection mode,” the drivesource 20 is inactive, but the temperature indicators 60 are activelymeasuring the surrounding temperature. If the control unit 50 determinesthat the rate of temperature change at any of the temperature indicators60 is greater than a predetermined threshold, the control unit 50 willidentify those temperature indicators 60 as the location of a fire. Thecontrol unit 50 will activate the drive source 20 and open the controlvalve 17 so that extinguishing medium may be supplied to the open sprayheads 40.

In another embodiment, during a normal detection mode, both the drivesource and the temperature indicators 60 are inactive; only the firesensors 45 are operative. When one of the fire sensors 45 detects thepresence of a fire, the fire sensor 45 sends a signal to the controlunit 50. The fire sensors 45 act as a general alarm, indicating to thefire suppression system 10 a need to determine the location of the fire.In response to the signal from the fire sensor 45, the control unit 50starts the drive source 20 and activates the temperature indicators 60connected to the fire suppression system 10. The control unit 50 willmonitor the change in temperature over time measured by each temperatureindicator 60. If the control unit 50 determines that the rate oftemperature change at any of the temperature indicators 60 is above apredetermined threshold, the control unit 50 will identify thosetemperature indicators 60 as adjacent the general location of a fire.Alternatively, the control unit 50 may identify the temperatureindicators 60 having the greatest rate of temperature change as adjacentthe general location of the fire. The control unit 50 will activate thedrive source 20 and open the control valve 17 so that extinguishingmedium may be supplied to the open spray heads 40.

A fire suppression system 10 responsive to a temperature rate of changeor temperature derivative will more efficiently and accurately determinethe location of a fire. By quickly providing exact information to abuilding owner about the location of a fire, it may be possible tomanually combat the fire at an earlier stage. The system 10 may also becapable of manually or automatically sharing the fire locationinformation with an external group responsive to fire alarms, such as anearby fire department for example. In addition, the improved firedetection accuracy allows the system to be more appropriatelydimensioned for a space, such that additional components, and thereforecost, may be removed from the system 10.

While the invention has been described in detail in connection with onlya limited number of embodiments, it should be readily understood thatthe invention is not limited to such disclosed embodiments. Rather, theinvention can be modified to incorporate any number of variations,alterations, substitutions or equivalent arrangements not heretoforedescribed, but which are commensurate with the spirit and scope of theinvention. Additionally, while various embodiments of the invention havebeen described, it is to be understood that aspects of the invention mayinclude only some of the described embodiments. Accordingly, theinvention is not to be seen as limited by the foregoing description, butis only limited by the scope of the appended claims.

1. A fire suppression system comprising: at least one spray head; adrive source coupled to the at least one spray head by a supply linethat delivers an extinguishing medium thereto; a plurality oftemperature indicators for measuring a surrounding temperature; and acontrol unit operably coupled to the drive source and the plurality oftemperature indicators, wherein the control unit monitors a rate ofchange of the temperature measured by each of the plurality oftemperature indicators to determine a location of a fire.
 2. The firesuppression system according to claim 1, wherein the control unitidentifies which temperature indicators have a highest rate oftemperature change to determine the location of the fire.
 3. The firesuppression system according to claim 1, wherein the control unitidentifies which temperature indicators have a rate of temperaturechange above a predetermined threshold to determine the location of thefire.
 4. The fire suppression system according to claim 1, wherein theplurality of temperature indicators are disposed within the supply lineadjacent the at least one spray head.
 5. The fire suppression systemaccording to claim 4, further comprising a control valve connected tothe supply line between the drive source and the at least one sprayhead, wherein a portion of the supply line extending from the controlvalve to the at least one spray head is filled with a gas.
 6. The firesuppression system according to claim 1, wherein the plurality oftemperature indicators measure an ambient temperature adjacent the atleast one spray head.
 7. The fire suppression system according to claim6, wherein the plurality of temperature indicators are mounted to aportion of the at least one spray head.
 8. The fire suppression systemaccording to claim 6, wherein the plurality of temperature indicatorsare located in a vicinity of the at least one spray head, externallyfrom the supply line.
 9. The fire suppression system according to claim1, further comprising: a plurality of fire sensors operably coupled tothe control unit, wherein activation of one of the plurality of firesensors provides a general alarm to the fire suppression system.
 10. Thefire suppression system according to claim 1, wherein the plurality oftemperature indicators are thermocouples.
 11. A method of activating afire suppression system having a plurality of temperature indicatorspositioned adjacent a plurality of spray heads, comprising: measuring asurrounding temperature at each of the plurality of temperatureindicators; calculating a change in temperature at each of the pluralityof temperature indicators over time; determining a location of a firebased on a rate of temperature change of each of the plurality oftemperature indicators; and activating the fire suppression system. 12.The method according to claim 11, wherein a control unit operablycoupled to the plurality of temperature indicators calculates the changein temperature at each of the plurality of temperature indicators overtime.
 13. The method according to claim 11, wherein the temperatureindicators having a rate of temperature change greater than apredetermined threshold indicate the location of the fire.
 14. Themethod according to claim 11, wherein the temperature indicators havinga fastest rate of temperature change indicate the location of the fire.15. A method of detecting and determining a location of a fire using afire suppression system having a plurality of temperature indicatorspositioned adjacent a plurality of spray heads and a plurality of firesensors coupled to the system, comprising: detecting a presence of afire; activating a drive source and the plurality of temperatureindicators; measuring a surrounding temperature at each of the pluralityof temperature indicators; calculating a rate of change in temperatureat each of the plurality of temperature indicators; determining alocation of a fire based on a rate of temperature change of each of theplurality of temperature indicators; and activating the fire suppressionsystem.
 16. The method according to claim 15, wherein the plurality offire sensors detect the presence of a fire.
 17. The method according toclaim 15, wherein a control unit activates the drive source and theplurality of temperature indicators after receiving a signal from atleast one of the plurality of fire sensors.
 18. The method according toclaim 15, wherein a control unit operably coupled to the plurality oftemperature indicators calculates the rate of change in temperature ateach of the plurality of temperature indicators.
 19. The methodaccording to claim 15, wherein the temperature indicators having a rateof temperature change greater than a predetermined threshold indicatethe location of the fire.
 20. The method according to claim 15, whereinthe temperature indicators having a fastest rate of temperature changeindicate the location of the fire.